In the conventional LED warning lamp market, the trend is toward lightbars containing light heads that can emit two or three or more colors. This is done so that in one mode the lights might be flashing red or blue and then in another mode they may switch to Amber or White. Dual- and even triple-color lamps are becoming common. This can get quite costly in lightbars with many lamps to control.
The standard way of implementing this is through lamps consisting of sets of LEDs of different colors behind an optical system designed for multiple LEDs. Most of these multicolor lamps then have many wires coming out of them (at least a common power wire and a wire for each color) and require a separate controller channel (like in a MOSFET or other power switch connected to the output of a microcontroller) for each color, doubling or tripling the number of channels required. A typical 48″ police lightbar, for example, might have around 20 lamps and a controller with 26 channels. To make this a triple color bar would require triple the number of channels and wires in the harness, requiring a much larger controller and a harness with many more wires and connectors, and with many more contacts. Harnesses and connectors are sources of potential failure.